LED lighting device having blue light warning means

Abstract

The present invention relates to an LED lighting device and, more specifically, to an LED lighting device having a blue light warning means with respect to aging of an LED. The LED lighting device having the blue light warning means, according to the present invention, comprises: a first optical sensor for sensing the intensity of a wavelength of green light emitted from the LED lighting device; a second optical sensor for sensing the intensity of a wavelength of blue light emitted from the LED lighting device; a calculation means for calculating a blue light risk ratio by receiving an output of each optical sensor; and a warning means for displaying the calculated blue light risk ratio, wherein the calculation means is configured to calculate a first blue light risk ratio (alpha = SB / SG), which is a ratio of an output (SG) of the first optical sensor and an output (SB) of the second optical sensor, and provide same to the warning means, and the warning means is configured to display a warning when the provided first blue light risk ratio is equal to or greater than a predetermined value.

Description

LED lighting device equipped with a blue light warning means

[0001] The present invention relates to an LED lighting device, and more specifically, to an LED lighting device equipped with a blue light warning means for the aging of an LED.

[0002] An LED (Light Emitting Diode) is a device that converts electrical energy into light energy and is used as a component in LED lighting devices. LED lighting devices can produce white light in two ways. The first method involves combining red, green, and blue LEDs to create white light. The second method involves combining a blue LED with green and red phosphors to obtain white light.

[0003] When white LED lighting devices are manufactured and shipped from the factory, their color temperature (CCT) and color rendering index (CRI) are determined according to the intended use of the lighting device. Figure 1 shows the wavelength distribution of LED lighting devices with color temperatures of 3000K and 6400K. For example, lighting devices with a color temperature of 2700K to 3000K are used for lighting that creates a warm and cozy atmosphere in bedrooms, living rooms, and dining rooms; lighting devices with a color temperature of 3500K to 4500K are used for lighting that creates a natural and bright feeling in kitchens, bathrooms, and offices; lighting devices with a color temperature of 5000K to 6500K are used for lighting that provides clarity and enhances concentration in workshops, commercial spaces, and hospitals; and lighting devices with a color temperature of 6500K or higher are used for lighting that requires very bright and cold light in factories, parking lots, and signboards.

[0004] Generally, LED lighting devices convert 20 to 40 percent of electrical energy into light, while the remainder is converted into heat. When LED lighting devices are used for extended periods, the heat generated causes the LED elements themselves to degrade, resulting in a decrease in light output. Additionally, the phosphor may be damaged by the heat generated, or its performance may be degraded due to chemical reactions between the phosphor and the encapsulant. Furthermore, changes in humidity and temperature at the location where the LED lighting device is installed and used also contribute to the aging and degradation of the device. As the LED lighting device degrades, the performance set at the time of shipment from the factory decreases, and this performance degradation causes a change in the wavelength distribution of the light.

[0005] Meanwhile, blue light has the shortest wavelength among visible light and possesses high energy, which can cause damage to the eyes. Regarding the harmful effects of blue light, prolonged exposure is known to increase eye fatigue, damage the retina leading to vision loss, suppress the secretion of melatonin (a sleep-inducing hormone) causing poor sleep quality, and affect the secretion of hormones that regulate circadian rhythms.

[0006] On the other hand, red light is known to have the function of protecting and regenerating the retina, helping to preserve eyesight in the long term by reducing eye fatigue, improving the quality of sleep by promoting melatonin secretion, aiding skin regeneration and wound healing processes, and providing psychological stability by giving a comfortable and warm feeling.

[0007] The light generated by LED lighting devices contains blue light. Additionally, sunlight also contains blue light. Although the brightness of sunlight is incomparably brighter than that of LED lighting devices, there is no warning regarding the risk of vision damage caused by the blue light contained in sunlight. However, if LED lighting devices are used for a long time and age, causing the proportion of blue light in the devices to increase, there is a risk of vision damage caused by the blue light.

[0008] [Prior Art Literature]

[0009] (Non-patent Document 1) Andrew J. Zele et al, Melanopsin and Cone Photoreceptor Inputs to the Afferent Pupil Light Response" Frontiers in Neurology.

[0010] (Non-patent Literature 2) Cheon Seong-il, Jang Jung-un, Accelerated Degradation Test of Phosphor-Converted High-Power White LED Package, Journal of the Microelectronics & Packaging Society Vol. 17, No. 4, p. 1-00. 2010.

[0011] (Non-patent Literature 3) Cheon Seong-il, Yoon Yang-gi, Jang Joong-soon, Accelerated Testing of High-Power Phosphor-Converted White LED Packages, The Korean Society for Reliability, Research on Reliability Applications 2010, vol. 10.

[0012] Although sunlight contains blue light and the amount of blue light is greater than that generated by typical LED lighting devices, it is necessary to examine why the blue light contained in sunlight does not damage eyesight.

[0013] The structure of the eye is illustrated in Fig. 2. As shown in Fig. 2, the human eye receives light through the pupil to perceive objects. The pupil is a circular opening located in the center of the eye and acts like the aperture of a camera. The size of the pupil is controlled by a muscular tissue called the iris, which adjusts the pupil size according to the intensity of light; this is called the pupillary reflex. The role of the pupil is to maintain vision by protecting the retina through the regulation of the amount of light entering the eye. In bright environments, the pupil constricts to prevent excessive light from reaching the retina, while in dark environments, the pupil dilates to allow as much light as possible to reach the retina.

[0014] The pupillary reflex is controlled by the autonomic nervous system, and the pupil responds according to the amount and wavelength of light. The visual sensitivity curve is a curve that indicates how sensitively the human eye responds to the wavelength of light. Figure 4 shows the visual sensitivity curve of the eye, and as illustrated, the human eye is known to be most sensitive to green light (555 nm). In Figure 4, the dotted line represents the visual sensitivity curve of a light-adapted eye, and the solid line represents the visual sensitivity curve of a dark-adapted eye. The eye is configured to constrict to protect the eye when there is a large amount of green light entering the pupil. In particular, blue-green light (approx. 480 nm) is the wavelength to which melanopsin responds most sensitively, and it is known that light stimulation of this wavelength activates intrinsic photosensitive retinal ganglion cells (ipRGCs) to induce the pupillary reflex (PLR) (Non-patent Literature 2).

[0015] Figure 3 illustrates the spectrum of sunlight. As can be seen from Figure 3, the relative intensity of the visible light region of the sunlight spectrum is nearly uniform. When there is a large amount of green light in the sunlight, the eye constricts the pupil to reduce the amount of blue light exposed to the retina, and when there is a small amount of green light, it dilates the pupil to increase the amount of blue light exposed to the retina. In other words, the eye is configured to adapt to sunlight in which the amounts of blue light and green light are evenly distributed, thereby protecting the eye from harmful blue light.

[0016] Unlike sunlight, LED lighting devices not only have an uneven ratio of red, green, and blue light but also contain a low amount of blue-green light. LED lighting devices produce white light by mixing blue LEDs with green and red phosphors in appropriate proportions. Furthermore, as LED lighting devices are used for extended periods, the ratios of red, green, and blue light set at the factory change due to degradation. If the amount of green light decreases as the LED lighting device ages, the eye dilates the pupil to receive the relatively increased blue light, potentially causing retinal damage. Therefore, to protect eyesight from blue light, it is necessary to warn the user whether the proportion of blue light emitted from the LED lighting device has increased. In other words, if the amount of blue light wavelengths increases relatively compared to the amount of green light wavelengths due to the aging of the LED lighting device, a means is required to warn the user to replace the LED lighting device to protect their eyesight.

[0017] The present invention aims to provide an LED lighting device equipped with a warning means for measuring the ratio of green light and blue light due to the aging of the LED lighting device and notifying the replacement of the LED lighting device to protect eyesight when the ratio differs from an initially set value by more than a certain value.

[0018] An LED lighting device equipped with a blue light warning means according to the present invention comprises a first light sensor for detecting the intensity of the wavelength of green light emitted from the LED lighting device, a second light sensor for detecting the intensity of the wavelength of blue light, a calculation means for receiving the output of each of the light sensors and calculating a blue light risk ratio, and a warning means for displaying the calculated blue light risk ratio. The calculation means calculates a first blue light risk ratio (alpha=SB / SG), which is the ratio of the output (SG) of the first light sensor and the output (SB) of the second light sensor, and provides it to the warning means. The warning means is configured to display a warning when the received first blue light risk ratio is greater than or equal to a predetermined value.

[0019] In some embodiments, the LED lighting device according to the present invention further includes a third light sensor for detecting the intensity of the wavelength of red light, and the calculation means calculates a second blue light risk ratio (beta=SB / SR), which is the ratio of the output (SR) of the third light sensor to the output (SB) of the second light sensor, and provides it to the warning means, and the warning means may be configured to display a warning by comparing the provided first blue light risk ratio and the second blue light risk ratio.

[0020] In some embodiments, the LED lighting device according to the present invention further includes a fourth light sensor for detecting the intensity of the wavelength of blue-green light, and the calculation means calculates a third blue light risk ratio (gamma = SB / (SG + SBG)), which is the ratio of the output (SBG) of the fourth light sensor and the output (SB) of the second light sensor, and provides it to the warning means, and the warning means may be configured to display a warning when the received third blue light risk ratio is greater than or equal to a predetermined value.

[0021] In some embodiments, it is preferable that the first photosensor has a peak wavelength in the range of 500 to 600 nm and the second photosensor has a peak wavelength in the range of 430 to 470 nm. Additionally, it is preferable that the third photosensor has a peak wavelength in the range of 600 to 700 nm and the fourth photosensor has a peak wavelength in the range of 470 to 490 nm.

[0022] In some embodiments, the LED lighting device according to the present invention may further include a transmission means for receiving and transmitting a risk ratio calculated from the calculation means to an external source.

[0023] The LED lighting device according to the present invention is equipped with means for warning of the danger of blue light, thereby enabling the user to replace the LED lighting device in a timely manner and thus protecting their eyesight. In addition, by enabling the timely replacement of the lighting device, energy waste caused by the aging of the lighting device can be prevented.

[0024] In addition, the LED lighting device according to the present invention is equipped with a transmission means capable of notifying the user of the risk of blue light damage when there is a risk of vision damage due to blue light from prolonged use. Accordingly, by enabling managers of large buildings to plan for replacing lighting devices that have reached the end of their lifespan, this not only prevents the deterioration of the user's vision but also contributes to energy saving.

[0025] Figure 1 is a wavelength distribution of LED lighting devices with color temperatures of 3000K and 6400K.

[0026] Figure 2 is a schematic diagram of the eye structure.

[0027] Figure 3 is the spectral distribution of sunlight in the visible light region.

[0028] Figure 4 is the visual sensitivity curve

[0029] Figure 5 is a graph showing the change in wavelength distribution due to the lighting degradation of the LED.

[0030] Figure 6 is a graph showing the change in wavelength distribution due to LED lighting degradation as changes in blue light wavelength ratio and color temperature.

[0031] Figure 7 is a graph showing the change in wavelength distribution due to aging of a high-power phosphor-converted white LED.

[0032] FIG. 8 is a graph showing the change in peak values ​​of blue light (455 nm) and green light (560 nm) according to temperature, and the change in the peak value ratio (455 nm / 560 nm) due to degradation.

[0033] FIG. 9 is a schematic diagram of an LED lighting device equipped with a blue light warning means according to the present invention.

[0034] FIG. 10 is a schematic diagram of an embodiment of an LED lighting device equipped with a blue light warning means according to the present invention.

[0035] FIG. 11 is a schematic diagram of another embodiment of an LED lighting device equipped with a blue light warning means according to the present invention.

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0037] LED lighting devices are known to contain more blue light compared to conventional lighting devices such as incandescent bulbs. In particular, since LED lighting devices that produce white light using phosphors are manufactured based on blue light LEDs, the wavelength distribution changes as the device ages or deteriorates. If LED lighting devices are used for a long time and undergo deterioration and aging, the color temperature and color rendering index set at the time of shipment from the factory change.

[0038] FIG. 5 is a graph reinterpreting the change in wavelength distribution due to the degradation of an LED in generally well-known color temperature units (Non-patent Literature 2). Although color temperature and blue light hazards do not always coincide, the change in color temperature in lighting with a similar wavelength distribution is similar to the change in blue light hazards. Therefore, this graph can be utilized to facilitate understanding of the present invention. As shown, when an LED with a color temperature of 5700K degrades to a color temperature of 6670K, the ratio of the intensity of blue light (455nm) decreases to 0.75 relative to the initial value, and the ratio of the intensity of green light (555nm) decreases to 0.45 relative to the initial value. Additionally, when the color temperature degrades to 7640K, the intensity of blue light (455nm) decreases to 0.53, and the intensity of green light (560nm) decreases to 0.31. In addition, when the color temperature degrades to 8910K, the intensity of the blue light (455nm) decreases to 0.33, and the intensity of the green light (555nm) decreases to 0.15. If the relationship between the change in color temperature and the wavelength ratio (455nm / 560nm) due to the degradation of the LED lighting is plotted, it results in a graph as shown in Fig. 6. As can be seen from Fig. 6, it can be observed that as the color temperature increases due to the aging of the LED, the ratio of the intensity of the blue light (455nm) to the green light (560nm) increases. The relationship equation for the change in color temperature and the ratio of the intensity of the blue light (455nm) to the green light (560nm) due to LED aging is as follows.

[0039]

[0040] Here, y is the color temperature and x is the wavelength ratio (x=455nm / 560nm)

[0041] Figure 7 is a graph showing the change in wavelength distribution due to aging of a high-power phosphor-converted white LED in a non-illuminated state (Non-patent Literature 3). The graph in Figure 7 is the result obtained by conducting a durability test by humidifying at temperatures of 110°C and 130°C without applying power. The changes in intensity of the 455 nm and 560 nm wavelengths due to aging of the center wavelength are summarized in the table below using the graph in Figure 7.

[0042] (Rate of decrease in maximum wavelength and ratio of blue light over time in accelerated life testing) Test Condition Center Wavelength 0h 100h 200h 300h 400h 500h 600h 700h 800h 110℃ 85% RH 455 nm 1.00 1.00 0.88 0.77 0.71 0.63 0.60 0.57 0.525 60 nm 1.00 0.99 0.92 0.85 0.79 0.75 0.73 0.70 0.67 455 / 560 1.00 1.01 0.96 0.91 0.90 0.84 0.82 0.81 0.78 130℃ 85% RH 455 nm 1.00 0.89 0.76 0.56 0.49 0.45 0.43 560nm1.000.960.880.780.710.710.68 455 / 5601.000.930.860.720.690.630.63

[0043] FIG. 8 is a graph showing the change in peak values ​​of blue light (455 nm) and green light (560) according to temperature, and the change in the peak value ratio (455 nm / 560 nm) according to degradation.

[0044] From Figures 7 and 8 and Table 1, it can be seen that during aging in the non-illuminated state, the degradation of the chip proceeds faster than the degradation of the phosphor, and the ratio of blue light decreases.

[0045] As previously discussed, when an LED lighting device that produces white light by combining a blue LED with a phosphor undergoes aging and degradation, it can be observed that the proportion of blue light increases due to the aging of the phosphor, and the proportion of blue light decreases due to the aging of the blue LED itself. The value representing the phenomenon where the proportion of blue light increases due to the aging of the phosphor is designated as the first blue light risk ratio (alpha) and is defined as follows.

[0046]

[0047] LED white light consists of a combination of green and red phosphors, and since phosphor aging is an inherent characteristic of the material, the aging mechanisms of green and red phosphors may differ. The value representing the change in the ratio of red light to blue light is called the second blue light risk ratio (beta) and is defined as follows.

[0048]

[0049] Referring to FIG. 9, a conventional LED lighting device (1) is composed of a power supply unit (10), an LED driver unit (20), and an LED array (30). A device called an SMPS (Switching Mode Power Supply) is commercially available for receiving AC power and driving the LED array (30) to light up, and it performs the functions of the power supply unit (10) and the LED driver unit (20).

[0050] The LED lighting device (100) according to the present invention comprises, in addition to the conventional LED lighting device (1), a light sensing unit (40), a calculation means (50) for receiving light detection output signals from light sensors (41-44) of the light sensing unit and calculating blue light risk ratios aplha and beta, and a warning means (60) for receiving the calculated blue light risk ratios (alpha, beta) and comparing them with a predetermined value to display a warning signal if the result is greater than or equal to the predetermined value. It also includes a transmission means (70) for transmitting the warning signal of the warning means (60) to the outside. The transmission means (70) includes wireless and / or wired communication means.

[0051] The light sensors (41-44) are sensors for detecting light of a specific wavelength emitted from an LED. The first light sensor (41) can detect a peak wavelength in the range of 500 to 600 nm, the second light sensor can detect a peak wavelength in the range of 430 to 470 nm, the third light sensor can detect a peak wavelength in the range of 600 to 700 nm, and the fourth light sensor can detect a peak wavelength in the range of 470 to 490 nm.

[0052] As described above, a monochromatic LED can be used as a light sensor to detect a defined wavelength range. Additionally, to detect specific wavelengths more accurately, a narrow-angle or luminous optical filter may be installed on the photodiode to allow only wavelengths within a selected range (red, green, cyan, blue) to pass through. Furthermore, an organic sensor may be used. Such sensing means are not difficult for a person of ordinary optical expertise.

[0053] The computation means (50) can be configured in an analog manner or implemented in a digital manner. For an analog computation means, it can be implemented by using an operational amplifier or by configuring an analog computation circuit. For a digital computation means, the signal from the optical sensor can be converted into a digital value and then implemented by configuring a digital circuit. Configuring such a computation means is not difficult for an ordinary electrical engineer.

[0054] The warning means (60) includes a display means for displaying a warning. As a display means, red, yellow, and green LEDs may be used to display the warning in color, an LCD may be used to display the warning as text or shapes, or a speaker may be used to display the warning as sound.

[0055] Referring to FIG. 9, the calculation means (50) is configured to calculate a first blue light risk ratio (alpha=SB / SG), which is the ratio of the output (SG) of the first light sensor (41) to the output (SB) of the second light sensor (42), and provide it to the warning means (60). Additionally, the warning means (60) is configured to display a warning if the received first blue light risk ratio is greater than or equal to a predetermined value.

[0056] When using a digital computation means, the computation means may perform the function of determining whether the calculated first blue light risk ratio (alpha=SB / SG) is greater than or equal to a predetermined value, and the warning means may be configured to merely display the determination result. In other words, when using a digital computation means, the computation means and the warning means may be logically distinguished, and a physical display means for showing the warning may be configured separately. In this case, the physical display means for showing the warning becomes part of the logical warning means.

[0057] FIG. 10 is a schematic diagram of one embodiment of an LED lighting device equipped with a blue light warning means according to the present invention.

[0058] Referring to FIG. 10, the first light sensor (SG) is a light sensor for detecting blue light, and the second light sensor (SB) is a light sensor for detecting green light. The LED lighting device of the present embodiment is a schematic diagram with the power supply unit and the LED driver unit omitted. Each light sensor (SB, SG) is configured to receive 9V of power from the LED array. In addition, the power supply is S B (Blue light) and S G (Green light) sensor, a differential amplifier which is a computing means (50), and three green, yellow, and blue LEDs which are warning means (60) are connected to drive. Blue light sensor S B and green light sensor S G Each generates a specific voltage signal according to the intensity of the blue light and green light, and the generated signal is transmitted to a differential amplifier (A).

[0059] The differential amplifier (A) receives voltage signals transmitted from light sensors SB and SG as input, calculates the output ratio of the two sensors alpha = SB output / SG output, and outputs it. The warning means (60) receives the output of the differential amplifier (A) and is configured to light up an LED among the output LEDs (green, yellow, blue) according to a preset condition based on the input value. For example, it is configured to light up the green LED when the alpha value is small (e.g., < 1.5), and when the alpha value is in the middle range (e.g., 1.5 B / S G <2.0) It can be configured so that green and yellow LEDs light up, and when the alpha value is large (e.g., > 2.0), it can be configured so that green, yellow, and blue LEDs light up. In addition, a Zener diode and a resistor are connected in series to the yellow and blue LEDs to distinguish the lighting voltage range and limit the current flowing through the LEDs. ​

[0060] The LED lighting device of the embodiment illustrated in FIG. 10 uses a 9V power supply from an LED array to transmit a signal detected through first and second light sensors (SG, SB) to a differential amplifier (A), and the differential amplifier (A) calculates a first blue light risk ratio in which the ratio of blue light increases due to the aging of the phosphor, and lights up the green, yellow, and blue LEDs of the warning means to indicate the degree of danger of blue light.

[0061] FIG. 11 is a schematic diagram of another embodiment of an LED lighting device equipped with a blue light warning means according to the present invention. The difference between the embodiment shown in FIG. 11 and the embodiment shown in FIG. 10 is that an SBG sensor is additionally installed in parallel with the SG sensor. The SBG sensor detects blue-green light and adds an auxiliary signal to the green light sensor SG, thereby affecting the output value of SG. By adding the SBG sensor, it is possible to provide an output value of SG that compensates for the retinal protection function of the pupil caused by the melatonin action of blue-green light. A differential amplifier (A) receives signals output from the SB, SG, and SBG sensors, calculates alpha = SB output / (SG output + SBG output), and outputs the result. An advantage of this embodiment is that it allows for more sophisticated signal analysis in detecting blue light hazards.

[0062] Although not illustrated, a sensor for detecting red light, SR, can be added in parallel to the light sensor unit (40) circuit of the embodiment of FIG. 10. Additionally, a differential amplifier can be added to the calculation means (50), and the ratio of the output of the blue light sensor SB and the output of the additionally installed red light sensor SR can be calculated and output. That is, the second blue light risk ratio beta = (SB output / SR output) can be calculated and output to represent the phenomenon where the ratio of blue light decreases due to the aging of the blue light LED itself. The second blue light risk ratio is an index to reflect the retinal protection mechanism of red light in the eye.

[0063] The warning means can be configured to display a warning by comparing alpha and beta values. For example, if the beta value is small, a compensated warning signal can be output so that the blue light risk is reduced and the blue light harm is mitigated.

[0064] The embodiments described above are not intended to limit the scope of the present invention. In addition to the embodiments described herein, various modifications, alterations, or substitutions may be made by those skilled in the art within the scope of the claims, and such modified embodiments should be understood to fall within the scope of the present invention.

Claims

1. In an LED lighting device, A first light sensor for detecting the intensity of the wavelength of green light emitted from the above LED lighting device, and a second light sensor for detecting the intensity of the wavelength of blue light, A calculation means for calculating a blue light risk ratio by receiving the output of each of the above-mentioned light sensors, and It includes a warning means for displaying the risk ratio of the blue light calculated above, and The above calculation means calculates a first blue light risk ratio (alpha = output of the second light sensor / output of the first light sensor), which is the ratio of the output of the first light sensor to the output of the second light sensor, and provides it to the warning means. The above warning means is an LED lighting device equipped with a blue light warning means configured to display a warning when the provided first blue light risk ratio is greater than or equal to a predetermined value.

2. In Paragraph 1, It further includes a third light sensor for detecting the intensity of the wavelength of red light, and The above calculation means calculates a second blue light risk ratio (beta = output of the second light sensor / output of the third light sensor), which is the ratio of the output of the third light sensor to the output of the second light sensor, and provides it to the warning means. An LED lighting device having a blue light warning means configured to compare a provided first blue light risk ratio and a second blue light risk ratio and to display a warning when the value of the first blue light risk ratio is greater than the value of the second blue light risk ratio.

3. In Paragraph 1, It further includes a fourth light sensor for detecting the intensity of the wavelength of blue-green light, and The above calculation means calculates a third blue light risk ratio (gamma=SB / (SG+SBG)), which is the ratio of the output (SBG) of the fourth light sensor and the output (SB) of the second light sensor, and provides it to the warning means. The above warning means is an LED lighting device equipped with a blue light warning means configured to display a warning when the provided third blue light risk ratio is greater than or equal to a predetermined value.

4. In Paragraph 1, An LED lighting device equipped with a blue light warning means, wherein the first optical sensor has a peak wavelength in the range of 500 to 600 nm and the second optical sensor has a peak wavelength in the range of 430 to 470 nm.

5. In Paragraph 2, The above third optical sensor is an LED lighting device equipped with a blue light warning means having a peak wavelength in the range of 600 to 700 nm.

6. In Paragraph 3, The above-mentioned fourth optical sensor is an LED lighting device equipped with a blue light warning means having a peak wavelength in the range of 470 to 490 nm.

7. In any one of paragraphs 1 through 6, An LED lighting device equipped with a blue light warning means, further comprising a transmission means for receiving a risk ratio calculated from the above-mentioned calculation means and transmitting it externally.

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